+1. It's probably a good idea to use MapAt with Unevaluated since you only need one modification for it to stop being a full array
–
RojoAug 9 '12 at 0:29

@Rojo that could work but Unevaluated is not a general solution (for example with List in place of {#1, #2} & which does not evaluate) so I think the second method may be more appropriate, and doing that for only one element would complicate things. (thanks for the vote.)
–
Mr.Wizard♦Aug 9 '12 at 3:18

I see your point. Perhaps this as ugly as it is could be more general Inner[List, list1, #, List] &[ MapAt[Sequence, Unevaluated[#] &[list2], {1, 1}]]. More general is still not general. It wouldn't work with HoldComplete instead of the first List
–
RojoAug 9 '12 at 3:32

Mathematica is a registered trademark of Wolfram Research, Inc. While the mark is used herein with the limited permission of Wolfram Research, Stack Exchange and this site disclaim all affiliation therewith.